


I Know! You Know! (That I'm Not Telling the Truth!)

by woodlands



Category: Teen Wolf (TV)
Genre: Alternate Universe - Fusion, Detectives, First Kiss, M/M
Language: English
Status: Completed
Published: 2012-01-01
Updated: 2012-01-01
Packaged: 2017-11-15 03:28:35
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 4,447
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/522646
Author URL: https://archiveofourown.org/users/woodlands/pseuds/woodlands
Summary: <blockquote class="userstuff">
              <p>Teen Wolf/Psych Fusion: </p><p>Stiles and Scott run the Psych Detective Agency and Derek just wants Stiles out of his hair. Stiles wants to make fun of Derek's hair.</p><p>...And maybe run his fingers through it, when he's not too busy solving muuuurders.</p>
            </blockquote>





	I Know! You Know! (That I'm Not Telling the Truth!)

**Author's Note:**

> Because I love Teen Wolf, and I love Psych. 
> 
> You don't really need to have watched Psych to read this, but if you haven't what the hell are you doing with your life, man.
> 
> (But if you haven't, all you need to know is that Stiles isn't _actually_ psychic. He just playin'.)

"Wait for iiiiiit," sings Stiles, wiggling his fingers in front of his face for a moment, looking around to see if anyone is indeed waiting for it. Nobody is, except for Derek, whose interest seems to begin and end with the intent of burning a hole through Stiles' face with his eyebrows. Which, yes, that's right: eyebrows. Because say what you will about Derek's iffy police work, his facial expressions are on their own level. Both metaphorically and on-his-face-physically.

Scott is staring dreamily at Allison, who works at the front desk and seems like she might actually be interested. Whenever they come in, Stiles catches her smiling at Scott, and Scott always becomes instantly useless. Leaving him at home has crossed Stiles' mind before, but it's not worth the loss of his own personal food retriever. All shortcomings aside, Scott can reasonably be relied upon for willingness to fetch froyo. 

Stiles elbows him in the side, hisses, "Come on, dude!" 

"Sorry," Scott mutters, looking down at the floor. "I was just--"

"ANYWAY," Stiles continues loudly, making several people in the area jump, "I'm getting a reading. And it's a big one, hoo boy. Really big. Like, hard to describe, big--"

"A penis did it!" Scott: ever helpful.

Stiles squints at him and shakes his head, but he's not too distracted to notice the way Derek half smiles, helplessly. "Thanks, buddy, but no. The spirits are telling me big, hard, ice. Like an iceberg? Greenberg? Green thumb?" He wiggles his thumb in the air a bit and chases his hand around Derek's desk, just for dramatics. "Does this mean anything to anyone?"

"No," Derek grouses, shoving off from where he's been standing with one hip canted to the wall, "Other than the deep translation of your uselessness."

Ignoring him, Stiles sits down on the floor abruptly. "The earth! Earth. My butt tells me that the earth is involved. Greenery, earth, potatoes? No, that's my stomach telling me I need curly fries. Scott, put that on our list of things to do immediately. Dirt? Check the purchase records of topsoil at the Green Thumb Garden Store!"

"Damnit," says Derek, and leaves. Erica Reyes, his partner, flips her hair and follows him. 

Later, when they're full of curly fries and milkshakes and Scott has finished waxing rhapsodic about Allison, he eyes Stiles with an accusing look. "Why didn't you make fun of Derek's tie?"

Plastering his most innocent look onto his face, Stiles takes a slurp from his milkshake. "Why would I do that?"

Scott frowns at him. "Last week you told him that black was too boring and he should try wearing blue sometime." He waves a hand. "And today, blue tie."

"Okay, well, look," begins Stiles, "He seemed kind of nervous about it. You know how Derek basically never displays emotions beyond 'angry', 'angrier', and 'smug'."

"So you didn't want to hurt his feelings."

"Yes. No!" He shrugs. This line of questioning is making him uncomfortable. "I don't think he has feelings."

They fist bump. The waitress brings them another plate of fries, which means someone's getting a sweet-ass tip today. 

"No but seriously," Scott insists, and Stiles, because Scott's like a dog sometimes, grabs hold of things and doesn't let go, no matter how much you snap your fingers at him. "Why're you taking it easy on Derek so much recently?"

Stiles isn't really very sure the best way to explain that he found Derek drunk alone at a bar last week, and Derek had looked at him with sad eyes and his hand had kind of twitched across the table at Stiles and he'd mumbled something about someone named Laura, and it hadn't taken Stiles very long to figure out the whole terrible story, and to put the dates together, and to understand. Which is why he hadn't said anything when Derek came into work the next day looking haunted, hungover, and another adjective which didn't start with an 'h', which was grumpy, with a 'g'.

Glancing down at the formica tabletop and stuffing more fries in his mouth as a distraction, he wracks his brain for a good excuse. Normally he's great at thinking on his feet, or just talking at someone until he gets to a point or they go away, but Scott is different; he always sees through that. There's a reason they've been friends for eighteen years.

"I'm saving up," is all he can come up with, "Lulling him into a false sense of security. And then, when he least expects it, BAM! Hit my favorite little detective with a hair joke!"

Scott snickers. "Misuse of great viral videos aside, good plan." And if that actually were the plan, Stiles would be swelling with pride.

So they solve more mysteries and do their thang, and Scott seems to have forgotten about the whole Derek thing. Stiles does too, on days when he doesn't go into the station and doesn't have to watch Derek do really mundane things in a really attractive manner. Because it's really frustrating--not to mention debilitating to his ability to pay attention to anything else, which is his job--when just watching Derek like, staple things makes his mouth dry.

One time, Chief Martin's baby projectile-vomited on Derek's uniform and he had to change shirts in the locker room, and Stiles totally had legitimate reasons to be there, he just can't remember what they were because Derek's abs.

Anyway.

They only solve one case in the next two months, and Stiles eventually gives in and cracks a joke about Derek's hair, because of boredom and because it's so hard not to when it could drive its own car, the amount of gel that's in it. Scott gets Allison to go on a date with him, which Stiles regrets not stopping somehow, because Scott just gets unbelievably more dreamy and silly. 

Chief Martin calls them on a Tuesday morning, and Scott is out getting them churros so Stiles is forced to answer the phone himself. He doesn't like doing that, especially when Chief Martin calls, because she's ever so-pretty and ever-so-evil and she always has some terrible, terrible news.

This time, it's this: "I can't put you on payroll for this."

But he agrees to do it, doesn't even ask what the actual case is, because it's Head Bitch In Charge Lydia Martin and she could tell him to strip naked and climb a flagpole and he'd do it. Or try to. Flagpole-climbing requires upper body strength which this model of Stiles does not come equipped with.

At the station, Scott grouses for all of six seconds before Stiles reminds him that Allison might be around, after which Scott straightens up quite a bit and surreptitiously fixes his hair in the nearest computer monitor. "What," he asks blankly, when Stiles smirks at him.

In Chief Martin's office, she motions for them to close the door and then leans back in the chair. She's already lost the weight she gained during her pregnancy, and Stiles takes a moment to appreciate all of that beauty in front of him before she glares and says, "I do carry a gun, you know." After that he shuts up and sits down, ignoring Scott's smirk.

"What can we do for you, Chief? What's the reason for all the secrecy? Need us to investigate that ne'er-do-well husband of yours?"

He's only met Jackson Whittemore once, but once is quite enough to know that he hates him. The way he hates hot sauce: a lot.

"No," sighs the Chief, "He doesn't have the balls to do anything stupid under my watch. I need you to investigate Derek."

Beside him, Scott makes a garbled noise. It's no secret that Scott is terrified of Derek. Stiles makes fun of him for it at any and all opportunity. 

He shifts in his seat. "Um. Why?" Then the possibilities hit him, and he grins. "Is he on drugs? Steroids, perhaps? Is he part of a cult? A leather, bondage cult? Have you seen his leather jacket? Is he--is he smuggling blood diamonds? Is that how he pays for his car?"

"Shut up, Stilinski." Chief Martin taps her nails against the top of her desk and frowns. "He's--he hasn't shown up to work today. And he didn't call out, and he never misses work. I'm… concerned."

Stiles has this theory, okay, that Derek is secretly a werewolf, which is obviously ludicrous but the fact is, it's a full moon tonight. Is it Stiles fault that the facts add up? Nope. 

"We'll take the case, Chief," he says, just as Scott says, "So we're not getting paid for this?"

-

Scott ditches him to go play video games with Isaac, who works with Scott at his actual job. So he takes the jeep out to the Hale House by himself. It's actually just an apartment, but Hale House sounds a lot like Haunted House. It fits in with the wolf metaphor. Disappointingly, the facade of the building is actually pretty cheerful, and the old lady who lets him in through the front gate smiles at him and isn't wearing a cape, so he probably should give up on the whole thing and accept the fact that Derek got his good looks the natural way--genetics, and maybe Maybelline. 

When he gets to Derek's door he realizes that he can't really knock on it, because then Derek will know what's up, and the investigation will be over and Chief will probably stab him in the eye with a pencil. So he knocks on the neighbor's door.

It's some middle-aged Korean man, who reacts the way most people do to Stiles, by gaping and not stopping him when he barrels on into the back of the--frankly, messy--living room and tries to climb out the window. "Don't worry, dude, I'm sorry I was so late but there was a lot of traffic, like, a gridlock, but I'll get your screen fixed super fast and your landlord is paying for it so don't even worry about it, although if you're worrying about the tip I usually go for about 50%--" As he says this he tries to take the screen off the window he's shoved open, but he doesn't know shit about home improvement and doesn't manage to do anything at all.

Eventually, when his plan totally fails, he pats the guy on his shoulder and shuts the door on the way out, frustrated to be back at square one. 

"Stiles?"

Square two is Derek-shaped, which is a great shape for a square to be. Stiles is aware he's getting a little off-track, mentally, but to be fair he wasn't expecting to be hit with the sight of Derek in anything other than straight-laced Detective Suit. Derek in a tee-shirt should be illegal. It's… endangerment of the public. Is that a thing?

"Uh," he says, brain still trying to catch up, because there are a lot of muscles in front of him, and it's really, really nice, "Heyyyyyyy, Derek…"

Derek glances back into his apartment quickly, surreptitiously, which he should probably know by now won't work on Stiles. Stiles notices things. That's his shtick. So instead of waiting for Derek's no-doubt snarky reply and attempt to get rid of him, he uses the element of surprise to push his way uninvited into the second apartment of the day, proclaiming loudly, "If there's something in here you wanted to hide, Derek, it's not gonna work because--"

He stops.

There's a woman in handcuffs on Derek's couch. 

Okay, unexpected. But Stiles can roll with it.

Maybe.

She's not naked, which is a start. And neither is Derek, which is also good, or bad, okay, the jury's out on that one. Stiles pauses and looks her over once, notes the unblemished skin around her wrists, the perfect curl of her hair, the smirk she's sporting. She's wearing a tight-fitting tank top and jeans, black leather boots that are sexy but are clearly also sensible, with tread on the the sole and tightly-laced sides. "You must be Stiles," she says, and her voice is deeper than he expects. 

"Uh, yeah," he says, wrong footed. "Derek likes to talk about me, I know."

The woman laughs, and it sounds awful, clear and cruel. It sparks a memory, a flash of a television screen, a muffled voice recording, the gravestones in Washington Cemetery. "You're Kate Argent," he accuses, and she looks surprised for a moment, like she's impressed. Stiles isn't fooled. "You're a serial murderer."

Kate Argent smirks. "Honey, I'm a hunter. World of a difference."

"There really isn't." Derek speaks up for the first time, crossing the room to stand next to Stiles, his shoulder bumping Stiles' for a moment. How he's remained so calm, Stiles doesn't know--if he had the woman responsible for the death of his entire family sitting on his couch, he'd be coming up with a strategy for dumping the body somewhere offshore.

To be honest, Derek could still be doing that. Stiles is pretty sure that Derek has wanted to kill him every time they're in the same room. And Stiles has accepted this fact, and moved on. Mostly. He's convinced that they'd have amazing sexual chemistry because of it. 

"It's a game, baby-doll," Kate says, "A chase. I hunt because I can. It's just that everyone always makes it so easy for me, don't they, Derek? You rolled over and begged me to burn your entire family to the ground."

The way she says it, cruel and proud, makes a sick shiver climb Stiles' spine. He pulls out his phone. "Ooookay, you're crazy. I'm calling backup, Derek."

"No," Derek growls, "I can take care of this."

"And what is this, sweet cheeks?" Kate asks, innocent and wide-eyed. "I thought we were just having a nice visit."

"Shut up."

She grins. "That's not how you treat guests."

"Shut up."

"You'd think you'd have better manners, Derek. Your parents were always so sweet to me. Remember that night? Your mother brought out chips and dip, just before I--"

Derek lunges at her, pins her to the couch, and growls, "Say another word, and I'll rip your throat out with my teeth." It's ferocious; Stiles has always known that Derek had it in him to be like this, that he operates on a coiled spring, but he's never seen it unleashed. There's something animalistic about it. It'd be kind of disturbing if it didn't kind of turn Stiles on just a teen tiny bit.

Stiles takes two steps backward, and then another, just to be safe. Surprisingly, Kate stays silent. 

Derek backs away, but nobody says anything, not even Stiles, who is seriously twitching with the need to say something. Instead he looks around the apartment, cataloguing everything, the spare decorations, the blank walls, the multitude of books on random things like Russian history, what looks like a photo album, several empty beer cans.

"Okay," he says, after a moment of silence, "I'm… Derek, where's your bathroom?"

Both Derek and Kate look at him like he's an idiot, but Derek nods his head in the direction of the bedroom, so Stiles gratefully slips away, glancing around the kitchen as he passes it. He'd expected it to be just as spare and empty as the rest of the apartment, but for some reason there's a pile of dishes in the sink and a Keurig next to a crappy toaster. Walking into the bedroom is a strange experience, because up until recently Stiles wasn't sure Derek even slept--there's significant evidence backing the claim that Derek never leaves the station except to eat and investigate. But he has a bed, which is unmade--and looks like it might be comfy, what the hell?--and there are clothes on the floor.

He calls Scott first. "Dude, I was this close to kicking Isaac's ass," Scott complains when he picks up, which begs the question: why even pick up in the first place? But there's no time for questions, so Stiles gets straight to the point.

"Scott! Derek has a murderer in his house! This is more important than your Bro Day with Bro 2." 

"Stop calling him that."

"Only if you start calling me Bro 1."

"Wait." There's a pause, and then Scott says, in a voice that means he's trying not to get too excited, "Did you say murderer?"

-

Stiles also calls his dad, who is less than thrilled about the length of time it took Stiles to call him about this. "It's practically obstruction of justice," he tells him, and Stiles can hear the door slam on the other end of the line. His dad's retired, but he sometimes consults for the department, and he still feels like he's relevant. "And before you ask, no, I'm not coming to get you. I'm hanging up on you and you're calling the actual police, and  I'm meeting you at the station."

And he does hang up. So Stiles pokes around in the bathroom for a bit, opening Derek's shampoo and smelling it, making an origami swan out of a piece of toilet paper, taking some pictures of himself in the bathroom mirror. He's thinking. There's something he's missing about this, something that doesn't add up.

Consider:

A. Derek didn't call out of work, something he never does, which either correlates to his love of privacy--but contradicts his love of following protocol-- or says something about the nature of the morning.

B. Derek didn't arrest her, not officially. The handcuffs probably don't count. 

C. Derek hasn't displayed any true animosity, aside from the whole growling thing.

D. Derek knows that Stiles is on the phone, calling Scott and his dad and, now, Erica, and he didn't try very hard to stop him. 

F. ????????

Stiles isn't sure what to make of all of it. Can't, for the life of him, figure out the last piece of the puzzle. So he dicks around for a little while longer, snoops in Derek's closet, checks the bedside drawer--nothing but a Colt 45 and another pair of handcuffs. Stiles prays fervently that the handcuffs have something to do with Derek's kinks. Just for kicks, he snags one of Derek's ties, because who knows when it will come in handy?

Eventually, he has to go back into the living room. Kate is sitting there in amused silence, while Derek paces in front of her. When Stiles comes in, Derek looks up, pauses, and then continues his pacing. "I called the station," Stiles announces, "So they'll be here in like five minutes to lock Crazy Kate up real tight."

Kate chuffs a laugh. "Good luck proving anything in court."

Derek freezes, and then frowns at Stiles like he wants Stiles to get something. Well, buddy, get in line. Stiles wants Stiles to understand something, too. 

Thankfully, the cops arrive. Erica doesn't even knock, just kicks in the door and assesses the situation flanked by Scott and Boyd, gun trained on Kate like the bad bitch she is. She actually gives him the shivers, that's how badass she is.

Stiles glances at Derek, and then just watches him. Derek looks calm. Not unconcerned, exactly, but unsurprised. It's frustrating and confusing, and while Erica pulls Kate to her feet and reads her her rights, Stiles wracks his brain, going over everything from the afternoon, yesterday, last week, last month. Having an eidetic memory comes in handy in crime solving, Stiles has always said. But it's kind of failing him now, the little… meanie.

Well, not completely.

Erica is looking at him semi-expectantly, and Scott is looking at him fully expectantly, and he knows how the evidence adds up.

He gears up to make a dramatic reveal, but something about the way Derek is carrying himself makes him pause. "The spirits are telling me the evidence is in the room with us," he says, as coolly as he can without making it look suspicious, "It's--a drawing? No. I'm getting, uh, a photo? Derek, do you have photos--?"

Scott pounces on the photo album Stiles had noticed earlier, flipping through it. He holds it up for everyone to see; the last page just has one photo, of a much younger Derek and what is probably his father, the edges blackened from fire. "Leave it in there," Erica hisses, when Scott tries to slip it out of its plastic cover, "You're fucking with evidence."

Later, Stiles follows the cops back to the station, where his dad is standing with his arms akimbo and a frown on his face that says _Stiles if you were any younger I'd be grounding you for sheer stupidity_ , which isn't exactly fair, since Stiles _did eventually call the cops_.

Kate gets locked up, and forensics identifies her fingerprints on the photo--she'd written a note on the back, _Hugs and Kisses, Kate_ \--liked the fucked up bitch she is. So Stiles is congratulated by the Chief, and Derek nods silently when one of the older cops tells him she's glad they've got the killer behind bars. But Stiles doesn't miss how Derek slips out early, and neither does Scott.

"Nice job," he says, holding up a fist for a bro-bump. "How'd you know about the photo?"

-

The thing is, Stiles isn't really sure. He'd seen the empty space on the bookshelf, and he'd noticed the photo album.

But what doesn't make sense is why Derek didn't bring Kate in himself? He'd gotten as far as handcuffing her to the couch, and he'd moved the evidence into plain sight. 

It didn't add--

wait

waaaaiiiiit

wait.

-

"Did you _let_ me solve that case?" 

Derek blinks at him, hand still on the door. "…What."

Stiles pushes past him for the second time today, whirls around, glares at him. Derek's still in the t-shirt, but he's lost the jeans and is just in his boxers, which is kind of distracting until Stiles remembers he's supposed to be mad. Or… something. Honestly he's mostly forgotten because Derek's dick is like, right under that cotton. 

He pulls himself together enough to point a finger. "You let me solve the case. Your case."

Derek rolls his eyes and glances pointedly between Stiles and the door. "Yeah, hi, Stiles, come on in."

"Stop deflecting!"

"Glad you could come over. Want something to drink?"

Stiles pauses. "Okay, yes. A beer. Is it too early for beer? Wait, no, come back, I'm trying to accuse you of--"

"--Stiles. No. I did not set you up to solve the case."

And it's a lie. Stiles can tell because his dad made him learn the top ten biggest tells when he was eight. He can tell because it's so obvious.

_It just doesn't make any sense._

He accepts the beer when Derek hands it to him, and takes a swig of it, watching Derek do the same. _Fuuuuuckokay_ , back on track. "Derek. Just, come on."

"You're the psychic, you figure it out."

"My psychic powers have hit a standstill. You're like a brick wall for my psychic radar. My brain spies can't spy your brain. Come on, man, you gotta give me something here."

Derek pauses, then smirks. "I just gave you a beer." He looks at Stiles sort of significantly, like that means something other than Derek making a joke that will go down in the records as one of the worst in history. 

Suddenly, though, Stiles gets it. His brain flashes through the beer, and then the entire contents of his dad's basement wet bar, and then the pouring of whiskey, and then Derek's face in the bar last month, quietly broken. And then later, a blue tie, a glance from Derek when Stiles came into the station to try to worm his way onto a case.

 _Oh_.

"Okay," he says, putting his beer down, "I don't understand _why_ you're doing this, but I understand why you're doing this."

"That doesn't make any sense."

Stiles thinks about stopping himself, but then he decides against it. "Derek, gimme your beer."

"Why."

Because Derek is clearly not willing to cooperate, Stiles swipes it before Derek can react. He puts it on the table next to his. When he turns around, Derek's a lot closer.

"You're a pain in the ass," Derek tells him.

"Thank you," says Stiles.

"This doesn't mean I'm letting you take any more of my cases."

"Derek, can we stop talking about murder and theft, please," Stiles complains, a little breathless. Derek's getting up close and personal, and Stiles can see his eyes and his pupils are dilated, holy _hell_. "All I'm saying is I feel like a moment might be happening here, and you're kind of ruining the sexy vibe with all this talk of policework--"

" _Do you ever shut up_."

"No--" 

Aaaaaaand they're kissing.

Sweet glory be Zeus God Odin, Derek can kiss. Stiles has gotten his share of mouth fun times over the years, but this is another fucking level; Derek throws his whole body into it, pulls Stiles against him, shoves fingers into Stiles' hair, sucks his lower lip. Totally on board with all of this, Stiles slides his palms down to Derek's ass, and it's like he's not wearing anything, his boxers are so thin. He hums happily against Derek's mouth.

"You--" 

"Yeah--"

"Fuck."

-

Later, when Scott calls to ask him where he went and why there are no more waffles in the office freezer, Stiles slips out from under Derek's arm and shuffles into the bathroom, pulls the door closed, looks at himself mostly-naked in the mirror, and whispers into the phone, "Scott, I have a mystery for you to solve."

"If the answer is 'grocery store' I'm gonna kill you, Stiles."

"No. Nope. What? I-- the mystery is, _who did I just get it in with_."

There's a pause on the other end, and then a long, drawn-out sound of absolute anguish.

" _Please tell me you didn't just have sex with Derek_. Stiles. _Please_."

" _I just had sex with Derek_."

Scott, the asshole, hangs up on him.

-

"Are you coming back to bed?"

Derek appears suddenly in the doorway, squinting down at Stiles, who is perched on the side of the tub, thinking. He looks up and tries not to whimper at the sight of all those abs. Yummmm. "Uh, do you want me to? I wasn't sure if you were hoping I'd let myself out around now."

"No. Come on." 

And who is Stiles to say no to another round of mind-blowing, semi-kinky sex with Derek Hale, resident hot cop and Best Kisser of the World, Possibly the Universe, Forever and Ever Amen?


End file.
